Causal
strong strength
Narrative Connection
How these two moments in the story relate
From
Susan Volunteers for the Mission
S1E6
·
The Survivors
To
Susan Forced Into Solo Mission
S1E6
·
The Survivors
Why These Connect
The narrative assertion
"The reveal of the drugs propels Ian and Barbara to attempt to retrieve them but because the Doctor is very ill Susan decides to go. This also highlights danger if someone attempts to tamper with it."
About Causal Connections
A directly causes B. The first event sets forces in motion that produce the second. These are the load-bearing connections of plot--remove one and the story structure collapses.